Dial kktob



Feb. 20, 1923..

c. P.WHITALL' DIAL KNOB Filed July 15, 1922 INVENTOR BY Mm! A ORNE SPatented Feb. 20, i923.

TENT orrics.

v CHARLES P. WHITALL, 0F LONG-MEADOW, MASSACHUSETTS.

DIAL KNOB.

Application filed July 13,

To all 'whomit may concern:

Be it known that I, Crmnnus P. lVHrrALL, citizen of the United States,residing at Longmeadow, in the county of Hampden and State ofMassachusetts, have invented new and useful Improvements in Dial Knobs,of which the following is a specification.

The present invention relates to dial knobs such as are used foradjusting various rotatable parts of radio apparatus.

The invention has for its object to provide an improved "molded dialknob of light but rugged "construction and of distinctive and pleasingappearance and one which is particularly well adapted for, economicalquantity production.

The invention consists in the novel-and advantageous features ofconstruction hereinafter described with reference to the accompanyingdrawings and defined in the appended claims. I

In the drawings i Fig. l is a view, in front elevation, of th improveddial knob;

Fig. 2 is a side elevational view thereof;

7 Fig. 3 is a detail sectional view'taken along the line 33 of Fig; 1;

'. line 55 of Fig. 1;

h Fig. 4c is a rear elevational view of the dial Fig. 5 is a sectionalview taken alongthe Fig. 6 is a perspective view of the dial knobshowing the rear side thereof; and

Fig. 7 is a rear elevational view of a dial knob of larger diametershowing a modified arrangement of stiffening ribs.

The illustrated dial knob comprises an annular dial portion 1 and acentrally disposed knob portion 2, the dial and knob portions beingintegrally formed of molded dielectric material. As shown clearly inFig. 5, the dial knob is ofshell-likeconstruction, the walls of theshell beingv made quite thin to save material and to reduce weight. Thedial portion is dished or in other words is formed with a flaring margin3 affording upon its outer sid ean annular'bevelled surface 4- bear- 1ing a Vernier 5 the graduationsof which are adapted to cooperate with asuitable mark or indicator (not shown) upon a stationary 1922. SerialNo. 574,835.

part of the radio apparatus. The hollow knob portion is offrusto-conical shape and its sloping side walls provide abevelledexterior which is knurled as indicated at 7 in Figs. 2 and 6. The smallor front end of the hollow knob is closed by an outwardly convex endwall 8 while the large or rear end of the knob is open and the side wallmerges, at the open end of the knob, with the inner peripheral portionof the dial.

To receive the spindlev or shaft of the rotatable element to which thedial knob is to be applied, an axially a-pertured hub 9 extends from theinner side of the front face of the knob portion 2. The free. extremityof the hub 9 projects outwardly beyond the plane of the outer rim of theannular dial portion, as shown. in Fig. 4, and serves to space the rimof the dial away from the adjacent face of the cabinet or other casingwhich encloses the apparatus carrying the dial knob and thus insuresample clearance between the movabledial and the stationary casing.

To strengthen and reinforce the shell-like sidewalls of the dial knoband particularly to stiffen the dished or bevelled portion of the dial,a plurality of radial ribs or webs 10 extend from the hub 9 to points onsaid side walls .'the stiffening ribs-preferably being equidistant fromeach other and extending in an axial direction from the end face of theknob portion to the plane of the outer rim of the dial'portion. In theform of dial shown in Figs. 1" to 6, inclusive, three radial stiffeningribs 10 are employed, but more or less could be used as may be founddesirable. In a dial knob of greater diameter it may be foundadvantageous to J provide four strengthening ribs such as indicated at10 in Fig. 6. I

In addition to stiffening and reinforcing the hollow shell of the dialknob the ribs 10 serve also to prevent distortion or warping of saidshell such as would cause the dial to wabble as it rotates. Inasmuch asthe dial carries the Vernier it is very desirable that the dial shallhave no tendency to wabble as it turns and consequently it will beappreciated that the ribs 10 perform an important function in preventingdistortion of the dial. In order that all the dial knobs molded in thesame mold shall be free from distortion and shall be precisely uniformin shape, the several radial ribs 10 are, in accordance with animportant feature of the present invention, syn'ln'ietrically disposedto avoid any tendency toward distortion of the dial such as might resultduring the setting or solidifying of themolded material if the radialribs were non-symmetrically arranged.

To enable the dial knob to be conveniently and fixedly secured to theshaft of the rotatable element to be adjusted, a screw threaded aperture1.2 extends radially through one of the ribs 10 from the exterior of theknohportion to the interior of the hub, this aperture being adapted toreceive a set-screw (not shown) for clamping the dial knob to itsshaft.v As shown, clearly at 13 in Fig. 3, the rib 10 through which theset screw is adapted to extend is .as the set-screw is tightened.

thickened to prevent it from being weakened by means of the set-screwreceiving aperture. By extending the set-screw aperture through one ofthe strengthening ribs 10, a greater area of threaded surface isprovided for engagement with the threads of the set-screw andconsequently there is less liability that the threads in the dial knobwill be stripped The importance of this feature will also be appreciated.when it is considered that the dielectric material such as is commonlyemployedofor making molded dial knobs is usually I more or less brittleand easily chipped... It will also be noted that the setscrew apertureis located adjacent, the base of the knob, i. e., adjacent:the endadjoining the dial thus insuring that the setscrew will engage a shaftwhich may fail to extend into the knob to the full depth of the aperturein the hub 9. This location employed in heavier and more bulky constructions. 'The mass of material is evenly distributed throughout thepresent dial knob and this feature, together with the employment of thereinforcing ribs 10 and the symmetrical arrangement of the latter,contributes to the production of a dial knob in which the tendency towarp is practically eliminated. Thus, although the dial knobs may beproduced in large quantities, the

finished articles will be uniform in shape and free from distortion.

The invention having been described, what is claimed is i l. A moldeddial knob comprising a central knob portion, a thin dished dial portionflaring outwardly from the knob portion, and radial reinforcing ribs onthe concave side of the dial portion.

2. A dial knob comprising a central knob portion, a thin dished dialportion flaring outwardly from one end of the knob, a central hubprojecting from said end of the knob, and a plurality of strengtheningribs radiating from said hub and merging with the concave side of thedial.

A dial knob comprising a-hollow central. knob open at one end, a dishedannular dial having its inner marginal portions merging with the sidewall of the knob at the open end of the latter, a hub projectinginwardly from the closed end of the knob and axially apertured for thereception of a shaft to be turned, and a plurality of stiffening ribsradiating in equally spaced apart relation from said hub and mergingwith said knob and dial along the inner surface of the knob andalong theconcave side of thedial from the inner to the outer periphery of thelatter.

4:. A dial knob comprising a hollow centralknob open at one end, adishedannular dial having its inner marginal portion merging with the sidewall of the knob at the open end of the latter, a hub projectinginwardly from the closed end of the knob and axially a-pertured for thereception of a shaft to be turned, and a plurality of stiffening'ribsradiating symmetrically from said hub and merging with said knob anddial along the inner surface of the knob and along the concave side ofthe dial, theside wall of said knob having a screw-threaded apertureextending radially therethrough in line With one of said ribs, saidaperture also extend ing through said rib and communicating with theaxial apertured in said hub to receive a setscrew for securing saidshaft to the dial knob.

5. A dial knob comprising ahollow central knob open-at one end, adishediannular dial having its inner marginal portions merging with theside wall of the knob at the open end of the latter, a hub projectinginwardly from the closed end of the knob and axially apertured for thereception of a shaft to be turned, and a plurality of. stiffening ribsradiating from said hub and merging with said knob and dial: along theinner surface of the knob and along the concave side of the dial fromthe inner to the outer periphery of the latter.

6. A dial knob comprising a hollow. knob portion closed at one end, athin dished dial portion flaring outwardly from the opposite end ofsaidknob portion, a hub integral with said closed end of the knobportion, said hub extending axially through the interior of the knobportion and projecting from the dial end of the knob to a point beyondthe plane of the-outer periphery of the dial portion, and a plurality ofportion and with the concave side of the dial 10 portion.

In testimony whereof I have afiixed my signature.

CHARLES P. WHITALL.

